Philips recently took action to protect its DVD+R patent rights by warning unlicensed disc makers in Taiwan and notifying customs agencies and distributors in Europe they should block imports from Taiwan makers who violate their patents, according to the warned makers.

Taiwan?s top producers of optical discs, including CMC Magnetics, Ritek and Prodisc Technology, are licensed to use Philips DVD+R technology, while second-tier and smaller makers are not licensed.

As Philips? DVD+R patents also cover CD-R technology, there is some ambiguity about the DVD+R royalty claim. This is why disc makers are unwilling to pay the royalty, unlicensed Taiwan users explained.

Although Philips has not yet taken legal proceedings, Taiwan optical disc makers that have received a warning from the company are watching to see how the situation develops.

In a related development, Philips lost a CD-R/RW patent suit in the US in March of this year against Taiwan makers, which means the company may have difficulty trying to claim royalty payments for its CD-R/RW patents.